package yukicoder

fun main() {
    val (h, w) = readLine()!!.split(" ").map(String::toInt)
    val blacks = (0 until h).flatMap { h2 ->
        readLine()!!
            .mapIndexed { index, c -> Pair(index, c) }
            .filter { it.second != '.' }
            .map { Pair(h2, it.first) }
    }

//    blacks.forEach { println(it) }
//    println("----------")

    if (blacks.size % 2 != 0) {
        println("NO")
        return
    }

    val redSize = blacks.size / 2
    fun canPaint(vararg redIndexes: Int): Boolean {
        return when (redIndexes.size >= redSize) {
            true -> {
                val redMasus = redIndexes.map { blacks[it] }
                val blueMasus = blacks.filter { !redMasus.contains(it) }

                for (i in 0 until h) {
                    for (j in 0 until w) {
                        if (i == 0 && j == 0) {
                            continue;
                        }
                        val movedReds = redMasus.map { Pair(it.first + i, it.second + j) }
                        if (movedReds == blueMasus) {
                            return true
                        }
                    }
                }
                return false
            }
            false -> (redIndexes.last() until redSize).map { canPaint(*redIndexes, it) }.any()
        }
    }
    when (canPaint(1)) {
        true -> println("YES")
        false -> println("NO")
    }
}